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from abc import ABCMeta, abstractmethod |
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from pyalgs.algorithms.graphs.topological_sort import DepthFirstOrder |
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from pyalgs.data_structures.graphs.graph import EdgeWeightedGraph, Digraph, DirectedEdgeWeightedGraph |
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7
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class ConnectedComponents(object): |
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marked = None |
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_id = None |
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_count = 0 |
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def __init__(self, G): |
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if isinstance(G, EdgeWeightedGraph): |
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G = G.to_graph() |
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vertex_count = G.vertex_count() |
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self.marked = [False] * vertex_count |
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self._id = [-1] * vertex_count |
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for v in range(vertex_count): |
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if not self.marked[v]: |
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self.dfs(G, v) |
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self._count += 1 |
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def dfs(self, G, v): |
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self.marked[v] = True |
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self._id[v] = self._count |
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for w in G.adj(v): |
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if not self.marked[w]: |
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self.dfs(G, w) |
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def connected(self, v, w): |
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return self._id[v] == self._id[w] |
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def count(self): |
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return self._count |
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def id(self, v): |
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return self._id[v] |
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class StronglyConnectedComponents(object): |
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marked = None |
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_id = None |
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_count = 0 |
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def __init__(self, G): |
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if isinstance(G, EdgeWeightedGraph): |
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raise ValueError('Graph must be directed graph for strongly connected components') |
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if isinstance(G, DirectedEdgeWeightedGraph): |
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G = G.to_digrah() |
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if not isinstance(G, Digraph): |
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raise ValueError('Graph must be directed graph for strongly connected components') |
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vertex_count = G.vertex_count() |
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self.marked = [False] * vertex_count |
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self._id = [-1] * vertex_count |
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dfo = DepthFirstOrder(G.reverse()) |
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orders = dfo.postOrder() |
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61
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for v in orders: |
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if not self.marked[v]: |
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self.dfs(G, v) |
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self._count += 1 |
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66
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def dfs(self, G, v): |
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self.marked[v] = True |
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self._id[v] = self._count |
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for w in G.adj(v): |
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if not self.marked[w]: |
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self.dfs(G, w) |
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def connected(self, v, w): |
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return self._id[v] == self._id[w] |
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def count(self): |
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return self._count |
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def id(self, v): |
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return self._id[v] |
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chen0040 /
pyalgs
